Toxic Caviar: Using Fish Embryos to Monitor Contaminant Impacts

One challenge in underwater research is conducting surveys to detect adverse ecological impacts. Surveys often rely on counting 'indicator organisms' to help identify impacts or changes in water and environmental quality. The scientific problem is that for a given environment, we must choose our 'canary' or indicator organism which best responds to the suspected perturbation. Once we have our indicator then we must decide what to measure and how to link measured effects to a specific stressor. I will provide an example of how quantifying developmental abnormalities in the embryos of a demersal spawning fish can be used as a monitoring tool or indicator of chemical contamination. This study investigated the use of developmental abnormalities as indicators of adverse effects in the reef damselfish, Abudefduf sordidus by comparing developmental abnormalities between PCB contaminated and uncontaminated areas within Johnston Atoll, Central Pacific Ocean. These results demonstrate that embryonic abnormalities in demersal spawning fishes can be used as an easily quantified metric for comparing contaminated and uncontaminated locations.